Don't import llvm.mk for non-portable builds.
Don't import llvm.mk for non-portable builds.

Change-Id: I447e7d816c0e4f84bc4d13bc34ff93b026d192b5

treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst